Opioid overdose is a leading cause of injury-related mortality in the United States.1,2 However, little is known nationally regarding the characteristics of opioid overdose presentations to emergency departments (EDs).

Methods

We analyzed the 2010 Nationwide Emergency Department Sample3 using diagnostic codes and mechanism of injury codes from the International Classification of Diseases, Ninth Revision, Clinical Modification, to define opioid overdose events. We tabulated ED visits by opioid type and aggregated charges and health care utilization data for the ED and inpatient care of patients presenting to the ED with opioid overdose. Nationwide Emergency Department Sample weights were applied to generate national estimates, and estimates for charges were generated with adjusted sample weights to account for missing data. We evaluated ED characteristics, demographic and clinical characteristics of the patients, and outcomes for prescription and nonprescription drug overdose events.

Results

In 2010, 135 971 weighted ED visits for opioid overdose were coded. Prescription opioids (including methadone) were involved in 67.8% of all overdoses, heroin in 16.1%, unspecified opioids in 13.4%, and multiple opioid types in 2.7% (Table 1). The proportion of visits resulting in death was highest for overdoses involving multiple opioids (2.2%) and lowest for prescription opioids (1.1%). For prescription overdoses, the greatest proportion occurred in urban areas (84.1%), in the South (40.2%), and among women (53.0%). Several comorbidities were common in our sample of overdose patients, including chronic mental (33.9%), circulatory (29.1%), and respiratory (25.6%) diseases. Of all overdose patients, 50.6% were admitted. Inpatient and ED charges for patients in our sample totaled nearly $2.3 billion (Table 2).

Discussion

Opioid overdose exacts a significant financial and health care utilization burden on the US health care system. Most patients in our sample overdosed on prescription opioids, suggesting that further efforts to stem the prescription opioid overdose epidemic are urgently needed. We observed marked regional variation in overdose patterns, with the highest burdens of prescription overdose found in the South and West.

Our study identified high rates of several comorbidities among patients presenting with overdose. This finding suggests that health care providers who prescribe opioid analgesics to patients with these comorbidities should do so with care and counsel all patients about the risk for overdose. In addition, acute benzodiazepine intoxication was recorded in 22.2% of all overdose patients, which highlights the need for cautious prescribing of opioids in conjunction with other sedating medications.4

Identification of trends in ED use for opioid overdose is also critical for planning overdose prevention efforts. For example, targeted interventions such as prescription monitoring programs and concomitantly prescribed take-home naloxone (an antidote for opioid overdose) may be particularly useful for patients who are prescribed opioids.5 Finally, the low mortality rate among patients presenting to EDs with overdose indicates that medical intervention for this acute condition can be highly effective. In our opinion, these findings support efforts to increase the use of emergency medical services for overdoses, such as Good Samaritan laws that grant limited immunity for drug-related charges to those who call 911 during an overdose.6

The economic and health care utilization burden that overdose exacts on US EDs and the health care system in general was substantial in our national sample. These findings suggest that the costs associated with opioid overdose are significant and that strategies to reduce morbidity and mortality resulting from overdose are urgently needed, including enhanced access to substance abuse treatment.

This study found 135 971 visits to US EDs for opioid overdose in 2010 alone. This number represents only a portion of all opioid overdoses because many individuals never present to an ED or die without activation of the emergency medical services system. Differences among patients presenting to EDs with opioid overdose have important implications for clinical and population-level overdose prevention efforts.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Yokell, Green.

Administrative, technical, or material support: Wang, Green.

Study supervision: Delgado, Zaller, Wang.

Conflict of Interest Disclosures: Dr Green reports employment in the past year at Inflexxion Inc, a small business that conducts postmarketing surveillance for scheduled medications. No other disclosures were reported.

Funding/Support: This study was supported by Stanford University School of Medicine (Mr Yokell and Dr Wang); by grant R21 CE002165-01 from the Centers for Disease Control and Prevention (CDC) (Dr Green); by grant UL1 RR025744 from the National Institutes of Health (NIH), National Center for Research Resources, and National Center for Advancing Translational Sciences (Dr Delgado); and by grant 5K12HL109009 from the National Heart, Lung, and Blood Institute (Dr Delgado).

Role of the Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. In addition, Inflexxion Inc had no role in the data analysis, interpretation of the findings, or decision to publish this research.

Disclaimer: The content of this study is solely the responsibility of the authors and does not represent the official views of the CDC, NIH, or Stanford University.

Previous Presentations: This study was presented at the American College of Emergency Physicians Scientific Forum; October 16, 2013; Seattle, Washington; and at the Panel on Integrating Public Health and Health Care Delivery, AcademyHealth Annual Research Meeting; June 10, 2014; San Diego, California.